Hey guys ive got a 2004 M6 GTO with the following mods:

Comp Custom Cam 228/230 .588/.592 112+ 2,59cc PRC stg 2.5 5.3's, Proxses modified 85mm ls6 intake, PP 85mm TB, Stainless Works LT'S with hollow cats, JBA Catback, Southbend Stg 2 clutch, Drag Bags, 06 Bumper, 06 Tails, 06 Brakes, MGW Proxses Modified shifter, AEM Brute force CAI, SLP 160 T-Stat, Green Top Injectors.


With all of the following mods on stock ls1 injectors I was getting 25-26 mpg and could get 27+ on occasion pretty easily (70mph highway cruise) not using lean cruise mode in Hp tuners.

Now with my Bosch Green Tops im only getting and average of 22-23 maybe 24 mpg 70 mph cruise same highway same basic temps as i only changed injectors few weeeks ago.

All the injector data has been in and my fuel trims look good just seems to eat more fuel for no apparent reason. Might try lean cruise mode in HP tuners but i never had to before.

What do you think is the problem? Any suggestions? Take them out and go back to stockers which were on like 90% duty cycle at wot or get another type of injector? Thanks in advance -Pete

Jon will have to correct me if I'm wrong, but a stock LS1 fuel system flows at 58 psi. I think it's like 28 lbs for a stock injector at that psi. Ford rates their injectors at 39.5 lbs. So a Ford 42 lb at 58 psi would be like 50.89 lbs in your car. Did you account for that? That's a big difference in injector size.

I am not a tuner, so take this all with a grain of salt and double check these numbers. There are several tuning sites and programs out there to help with the values you need to input into your tables.

Matthew

thanks for the reply and yep we have accounted for all of that and even put in the other injector settings needed thus far

it would be nice to see all of the flow data and voltage offsets etc to verify we input the correct numbers

I think you need to tell the ECM that you have different display fuel flow. On my C4 vettes the constant is called "display injector fuel rate" and it needs to be changed to show our new fuel economy. Its a formula of weight of fuel to pounds per hour.
The display injector flow rate is used for the instant/average miles per gallon in the DIC. When using a larger injector than stock, I divide the new injectors flow rate by 5.85 to correct the fuel mileage display